2025 & 2026 · Federal investment planning

Capital Gains
Tax Estimator

Estimate the added federal income tax on supported net short- and long-term investment gains. See how deductions and ordinary income affect the long-term rate bands, then add verified NIIT inputs for a combined estimate. This free calculator supports 2025 and 2026 individual planning. Loss netting, special asset rules and state taxes need separate review; the result is not a refund or payment calculation.

Free, no sign-up · Visible assumptions · Checked Oct. 9, 2026

YOUR GAINS, IN CONTEXT

See the added federal tax.

Separate your net gains, then see where each dollar lands.

Free, no account

Your investment scenario

After AGI adjustments, before deductions. Exclude the gains below, qualified dividends and other preferential income.

Already netted positive investment gains, generally held one year or less. Blank means 0.

Already netted positive gains eligible for ordinary 0%, 15% or 20% rates, generally held more than one year. Blank means 0.

Net losses and carryovers first using the applicable rules. Collectibles, home sales, business property and recapture need separate review.

Basic amount assumes eligibility: no dependent, age/blindness add-on or spouse-itemizing restriction. Custom amount stays fixed in both scenarios.

Optional: complete the NIIT estimate

Leave either blank if unknown. Supply baseline values before these gains; all entered gains are assumed subject to NIIT. This is separate from taxable income.

Verified modified adjusted gross income for NIIT, before the entered gains.

Verified net investment income before the entered gains. Include applicable other investment income and deductions; enter 0 only when verified.

2026 FEDERAL PLANNINGBefore → after

Income-tax estimate; NIIT unfinished

Sample scenario: $75,000 ordinary income and $20,000 long-term gains. NIIT inputs are unknown.

Added income tax$3,000.00

Short-term + long-term income-tax effect

Tax before: $7,670.00
Tax after: $10,670.00
Added NIIT · 3.8%Unknown

Enter both baseline NIIT inputs

MAGI threshold: $200,000.00
Combined added federal estimateNIIT inputs needed

The income-tax subtotal excludes unknown NIIT. No full federal total is shown. State taxes and other return effects are excluded.

Follow the income stack

Fixed deduction used
$16,100.00
Taxable ordinary income, including short-term
$58,900.00
Taxable long-term gains after deduction
$20,000.00
Added ordinary tax from short-term gains
$0.00

Long-term gain bands before worksheet comparison

0%$0.00 gains → $0.00 tax
Total taxable-income ceiling: $49,450.00
15%$20,000.00 gains → $3,000.00 tax
Total taxable-income ceiling: $545,500.00
20%$0.00 gains → $0.00 tax
Above the 15% ceiling

Band tax: $3,000.00. Ordinary-rate comparison reduction: $0.00. Long-term tax used: $3,000.00. The worksheet uses the lower of the preferential calculation and ordinary tax on all taxable income.

Long-term gains stack above taxable ordinary income. A 0% long-term band does not mean your whole return has no tax. Unused deductions can reduce taxable gains. This estimate assumes no other preferential income.

NIIT calculation

Baseline NIIT
Unknown
NIIT with entered gains
Unknown

Each scenario uses 3.8% × the smaller of net investment income or positive MAGI above the threshold. Deductions from taxable income do not automatically reduce MAGI for NIIT.

Records to prepare

0/4 ready
Supported scope & assumptions

2025/2026 federal individual planning with positive, already-netted ordinary short-term and 0/15/20% long-term investment gains. No existing qualified dividends or other preferential income. Ordinary income is after AGI adjustments, before deductions. The same fixed deduction applies before and after gains. Excludes loss/carryover/wash-sale calculations, special-rate assets, home-sale exclusions, depreciation/recapture, business sales, foreign rules, dependents, extra age/blindness deductions, AMT, credits, QBI, income-driven deduction changes, state tax and payment/refund estimates. Optional NIIT assumes all entered gains are subject to NIIT and requires verified baseline MAGI and net investment income. Rate-schedule estimates rounded to cents can differ from IRS tables and return worksheets.

Status: Single. Record readiness is self-reported.

Published by IntegraFin Tax & Accounting. Rules checked Oct. 9, 2026. Planning only; no election, sale or return is filed.

Review your investment taxes
Try an illustration

Three steps behind your estimate

01 · Verify the gain

Confirm adjusted basis, holding periods and netting. Enter positive net short- and long-term gains in the supported ordinary categories.

02 · Stack taxable income

Apply the fixed deduction to ordinary income first, then remaining long-term gain. Tax short-term gains at ordinary rates and long-term layers at 0%, 15% or 20%.

03 · Compare before and after

Subtract baseline income tax from modeled tax after gains. If NIIT inputs are known, add only the increase in NIIT, using separate MAGI and investment-income limits.

Two 2026 illustrations

A gain crosses the zero-rate ceiling

Single filer, $40,000 ordinary income, $30,000 long-term gain and $16,100 basic deduction: $23,900 taxable ordinary income leaves $25,550 of the gain at 0%. The remaining $4,450 is at 15%, for $667.50 added income tax. With verified $40,000 baseline MAGI and $0 baseline NII, added NIIT is $0.

Mixed gains cross the NIIT threshold

Single filer, $195,000 ordinary income, $10,000 short-term gain and $20,000 long-term gain: added ordinary tax is $2,400, long-term tax $3,000. With verified $195,000 baseline MAGI and $0 baseline NII, post-gain MAGI is $225,000 and NII is $30,000; NIIT adds $950. Combined modeled increase: $6,350.

Illustrations assume the supported scope and deduction eligibility; they are not client results or recommendations to sell.

Capital gains questions

How are short-term and long-term capital gains taxed?

Ordinary short-term investment gains are generally taxed at ordinary income rates. Eligible long-term gains generally use 0%, 15% or 20% rates based on total taxable income. This tool models already-netted positive gains in those categories; special-rate gains are excluded.

What counts as a long-term holding period?

Generally, more than one year is long term; one year or less is short term. Count from the day after acquisition through the disposal date. Inherited assets, gifts and certain other assets have exceptions; verify classification before entering amounts.

Why does ordinary income affect long-term tax?

Taxable long-term gains stack above taxable ordinary income, including short-term gains. Ordinary income uses some of the lower-rate band space. A large gain can span several rate bands instead of being taxed entirely at one rate.

Does this calculator include the 3.8% NIIT?

Only when both baseline MAGI and baseline net investment income are supplied. It compares NIIT before and after the entered gains, assuming those gains are fully NIIT-subject. Unknown inputs leave NIIT and the combined estimate unknown. NIIT is separate from the Additional Medicare Tax.

Should I enter sale proceeds or my gain?

Enter the supported net gain, not sale proceeds. Gain generally reflects amount realized minus adjusted basis. Confirm selling costs, basis adjustments and loss netting first. This calculator does not establish basis or perform sale-by-sale netting.

Can I enter capital losses or carryovers?

No negative amounts are supported. Review short- and long-term losses, carryovers and wash sales before entering positive net gains. Overall net losses and their ordinary-income deduction/carryforward need a separate calculation.

Does this work for a home sale, rental property or collectibles?

Those transactions need separate review. Home-sale exclusions, collectibles, Section 1202, business property, depreciation recapture and unrecaptured Section 1250 gains are outside the ordinary investment scope.

Does a zero-percent gain band mean I owe no tax?

No. It refers only to gain allocated to that long-term income-tax band. Short-term gains, NIIT, other income and state taxes may still create tax. This is an added-tax scenario estimate, not a balance due or refund.

Which deduction does the calculator use?

Choose the basic standard deduction if eligible, or a verified custom deduction. Dependents, age/blindness additions, a spouse who itemizes and income-driven deduction changes are not modeled. The same deduction is used before and after gains.

Scope & official sources

2025/2026 federal individual planning with positive, already-netted ordinary short-term and 0/15/20% long-term investment gains. No existing qualified dividends or other preferential income. Ordinary income is after AGI adjustments, before deductions. The same fixed deduction applies before and after gains. Excludes loss/carryover/wash-sale calculations, special-rate assets, home-sale exclusions, depreciation/recapture, business sales, foreign rules, dependents, extra age/blindness deductions, AMT, credits, QBI, income-driven deduction changes, state tax and payment/refund estimates. Optional NIIT assumes all entered gains are subject to NIIT and requires verified baseline MAGI and net investment income. Rate-schedule estimates rounded to cents can differ from IRS tables and return worksheets.

The $1 billion per-input limit is a product limit, not an IRS gain limit. Publication 550 and Form 1040 instructions currently cover 2025; 2026 uses published rate schedules for planning. Checked October 9, 2026. Published by IntegraFin Tax & Accounting.